Magnesium base alloys



Patented May 23, 1933 UNITED STATES PATENT OFFICE JOHN A. GANN AND JAMES B. REID, F MIDLAND, MICHIGAN, ASSIGNORS TO THE DOW CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN MAGNESIUM BASE ALLOYS No Drawing.

ceeds.

Our new alloys relate specifically to im-- provements over the known binary magnesium-cadmium alloys in which magnesium is present in excess of 80 per cent. Heretofore these alloys have not been widely employed as light structural metals due to their deficiency in tensile strength, yield point, and other necessary mechanical properties, and so far as we are aware no one has developed improved ternary alloys from the aforementioned binary alloys as a base. We have discovered that by adding relatively small amounts of manganese to the magnesium-cadmium binary alloys valuable new ternary alloys may be obtained which are superior to the simple magnesium-cadmium binary alloys. Accordingly, the alloys which are the subject of our invention contain the three metals magnesium, cadmium, and manganese, wherein the magnesium is present in excess of 80 per cent and the cadmium content may be from 0.5 to 18 per cent, while the manga'- nose content is from"0.5 to 2 per cent.

' As an example of the improvements obtainable by our adding manganese to the binary magnesium-cadmium alloy, the following table is inserted giving some of the properties possesed by these new ternary alloys, which may be compared with the prop- Application filed February 15, 1932. Serial No. 593,194.

cities of the binary magnesium-cadmium alloys also given.

Table Yield Elonga- Alloy compositiongggggfi: pointtion per 552%? approxlmate lbs/sq. in. if gz ness Ezrtruded 7 Mg 94%, Cd 6% 33, 000 16, 000 11% 12 ME 92%, Cd 6%, Mn 1.5%. 40, 000 27, 200 9% 15 Cast Mg 94%. Cd 6% 20, 000 4, 500 10% 8 Mg 92 0, Cd 67;, M1! 1.5%. 21, 000 4, 500 12% Thus the data in the table show that extruded samples of our new alloys exhibit a marked improvement in properties over the simple binary magnesium-cadmium alloy, particularly in regard to toughness, tensile strength, and yield point (defined as the load in lbs/sq. in. at which the stress-strain curve deviates 0.1 per cent elongation from the modulus line). We have found also that the addition of about 1.5 per cent of manganese'to the magnesium-cadmium binary alloys containing from 6 to 14 per cent cadmium further improves the yield point and at the same time the percentage elongation varies from about 8 to 10 per cent,vbeing lower the higher the cadmium content.

Our new alloys in the as cast condition also show improved properties over the simple magnesium-cadmium binary alloys; This improvement in properties, such as those shown 70 in the table for the cast alloys, may also be obtained when manganese is added to the magnesium alloys with a still greater cadmium content. For example, additions of manganese in amounts from L5 to 2.0 per cent effectively improve the yield point tensile strength, and toughness of the alloys in the as cast condition containing up to 18 per cent of cadmium. The percentage elongation of the cast magnesium-cadmium'binary alloy containing from 1 to 10 per cent of cadmium is also increased from about 6 per cent to about 8 per cent by the addition of from 1 to 2.0 per cent of manganese.

The compositions suitable for casting mayhave a magnesium content in excess of 80 per cent and a cadmium content from 0.5 to 18 per cent while the manganese content may vary from 0.5 to 2 per cent. A preferred casting composition, however, should have a manganese content from 0.5 to 2 per cent, while the cadmium content is from about 4-to 12 per cent. The malleability of these alloys tends to decrease as the cadmium content exceeds 10 per cent. The alloys coming within the scope of this invention that may be extruded readily may contain from 1 to 10 per cent of cadmium and from 0.5 to 2 per cent of manganese.

The manganese content of these alloys effective to modify the properties in accordance with our invention is that which can be permanently alloyed therewith. The maximum quantity of manganese which can be permanently alloyed with magnesium containing from 0.5 to 18 per cent of cadmium is approximately 2 per cent and such manganese appears to be dissolved in the alloy and can remain therein in solid solution in amounts up to about 2 per cent. The preferred quantity of manganese to employ in these alloys is the maximum which can be alloyed therewith, but owing to the well known difficulty with which manganese may be alloyed with magnesium somewhat less than 2 per cent may be employed generally.

The good resistance to corrosion possessed by these new ternary alloys combined with their strength and characteristic light weight adapt them to many uses in the mechanical arts where such a combination of properties is essential.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the proportions of the ingredients employed within the limits specified, provided the ingredients stated by any of the following claims or the equivalent of such stated ingredients be employed.

We therefore particularly point out and distinctly claim as our invention 1. As a new product, a magnesium base alloy composed of magnesium, cadmium, and

mium, and from 1 to 2 per cent of manganese.

3. As a new product, a magnesium base alloy composed of approximately 92 per cent of magnesium, approximately 6 per cent of cadmium, and approximately 1.5 per cent of manganese.

4. As a new product, a magnesium base alloy composed of more than 80 per cent of magnesium and from 4 to 12 per cent of cadmium and from 0.5 to 2 per cent of manganese.

Signed by us this 10th day of February,

JOH A. GANN. JAM S B. REID manganese, wherein the content of magnesium is in excess of 80 per cent, that of cadmium from 0.5 to 18 per cent, and that of manganese from 0.5 to 2 per cent.

2. As a new product, a magnesium base alloy composed of more than 80 per cent of magnesium, from 1 to 10 per cent of cad- CERTIFICATE or CORRECTION.

Patent No. 1,910,432. May 23,1933;

JOHN A. GANN, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, line 39, for "possesed" read "possessed"; line 54, in last line and column of the table, insert the numeral "12"; line 81, after "point" insert a comma; and that the said Letters Patent should he read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 22nd day of August, A. D. 1933.

M. J. Moore.

(Seal) I Acting Commissioner of Patents. 

